The present invention relates to a combined apparatus for the machining of articles manufactured from solid stone, glass, ceramic and metallic materials. Even more specifically the present invention relates to a numerical control apparatus with interpolated axes for cutting, along straight and curved lines, articles in the form of slabs. It is understood that the reference to slabs made of natural stone, natural stone conglomerates and ceramic material in the remainder of this description does not have a limiting nature, but is only an example of articles which may be machined by the apparatus.
In the field of machining stone, glass, ceramic or metallic materials, numerical control apparatuses, known as bridge cutting machines, are known. By means of a spindle on which a tool consisting of a rotary disk is mounted, these apparatuses perform cutting of slabs into polygonal elements with straight sides.
Numerical-control cutting apparatuses with a gantry structure have recently been designed and manufactured, in which the cutting disk may also be inclined in any position between 0° and 90°, with the possibility of performing also incrementally inclined cuts.
In a typical configuration of these apparatus, the tool-holder spindle is mounted on a beam which is enabled to perform a translatory movement with respect to the support surface and consequently with respect to the slab to be cut, while the spindle is in turn slidable along the beam, so that machining may be performed with considerable precision in the desired portion or portions of the slab.
An industrially important characteristic feature of these apparatus consists in the fact that very high cutting speeds together with a notable structural simplicity and equally notable mechanical strength may be obtained.
A problem hitherto unresolved of these numerical control gantry-type cutting apparatus is that of performing a transverse (either perpendicular or oblique) cut into polygonal elements having a size different from the parallel and adjacent strips resulting from the pass of the cutting disk in the longitudinal direction.
In fact, if the individual strips are engaged by the cutting disk in order to perform the transverse cut, at the end of the transverse cut of a first strip, the disk inevitably makes a nick in a second strip immediately adjacent to the first.
When the transverse cuts are not aligned in adjacent strips, it is obvious that the transverse cutting operation into elements of varying size may be performed only after separating the individual strips, removing them from the working surface or moving them away from each other the amount necessary such that the transverse cut of a strip does not also affect the immediately adjacent strip.
Also known is the technology of water-jet cutting of solid stone, glass, ceramic or metallic materials performed using apparatus where a jet of water emitted from a nozzle, movable along a controlled trajectory, is directed onto the surface of the article to be cut.
The water is emitted from the nozzle at a very high pressure (in the region of 3000-4000 bar) and, when it is required to cut hard materials, it is preferably mixed with suspended granules of abrasive materials.
Usually the material to be cut lays on a metal grid in turn mounted above a tank which is filled with water, said tank not only permitting the cutting water to be recycled, but also damping the violent impact of the jet emitted by the nozzle and passing through the material.
An advantageous characteristic feature of water jet cutting consists in the high cutting precision which allows the zone and extent of the cut to be determined in an exact manner: it is precisely because of this characteristic feature that water jet cutting apparatuses enable to perform cuts along profiles which are not straight.
Obviously, the use of water-jet cutting must be justified by particular machining requirements, in view of the higher operating cost.
There exist, however, situations and machining operations where it is desirable to be able to use both rotary-disk cutting technology and water-jet cutting technology. Hitherto this possibility may be realized only if both the apparatus in question are available.
In fact, it was not unusual, starting with a rough slab, to perform firstly longitudinal cuts, by means of which the slab is divided up into longitudinal strips having widths, which may also be different from each other. For this operation, the preferred tool is a rotary cutting disk and the apparatus used is a numerical-control cutting machine with a gantry structure.
Then it may be required to perform, for each strip, transverse cuts or also cuts not in a straight line, in particular along curved profiles, for which it is preferable to use a water jet cutting apparatus.
Finally, there exist intermediate situations where it is preferable to use both technologies and therefore both of said apparatuses for execution and completion of a same cut.